DESCRIPTION: (Adapted from applicants abstract) Despite the fact that vaginal birth is a recognized factor in the etiology of urinary incontinence (UI) across the life span, the impact of birthing events on urinary continence mechanisms is not well understood. An experimental pre-posttest design will be used with one experimental and one control group to prospectively study the effect of maternal pushing during second stage of labor on the function of the urinary continence mechanisms. The independent variable to be manipulated is type of maternal pushing: non-directed, spontaneous pushing (experimental group) and directed, sustained pushing (control group). Women will be assigned using a blocked randomization procedure to maintain provider balance between certified nurse-midwives (CNM) and obstetricians (MD). The experimental group will attend a class which the research-base for non- directed, spontaneous pushing as a protective strategy in decreasing the risk of UI will be presented. In addition, both the experimental and control groups will receive information on the benefits and techniques of pelvic muscle exercise (PME) as developed in the Principal Investigator's earlier work. The investigators have shown that PME improves postpartum pelvic muscle strength and urethral support. Thus, it is important that this strategy be incorporated into the proposed care of both groups so that PME influences do not confound the analysis of pushing type effects. A trained nurse observer will attend all births to document the expulsive phase of birth. Data on maternal birthing position, use of operative procedures, duration of second stage of labor, infant presentation and position, infant weight, and cord blood pH will also be obtained. The outcome variable of postpartum perineal and perivaginal tissue integrity will be assessed by a trained observer. Baseline data on the function of the urinary continence mechanisms will be collected at 20 weeks gestation. Specifically, women will provide information about UI symptoms and the investigators will conduct procedures to assess pelvic muscle strength and function (via clinical measures and computer-based gynecologic speculum), urine leak point pressure (via manometer), and urethral support (via ultrasound). Repeated measures will occur at 35 weeks gestation, 6 weeks postpartum, 6 months postpartum, and 12 months postpartum. This research will provide much needed data about specific childbirth-related mechanisms of UI. While the focus of the study is at the time of childbirth, the knowledge gained will benefit women throughout their post-childbearing years.